The British Library made 14 great books available online for you to leaf through at Turning the Pages. Among them are sketches by Leonardo, the History of England by Jane Austen’s and the original Alice in Wonderland written and illustrated by Lewis Carrol. You can even have a narrator read the works to you. Shockwave plug-in required except for three books of which alternative versions are available.
Link via Schockwellenreiter.
This reminds me of two other sites where you can browse old books:
The Cornell University Library Windows on the Past consists of several collections on various topics, among them Historical Math Monographs, which I used to read a book one wasn’t allowed to check out of my university’s library when writing my first thesis.